The most easily accessible examples of prehistoric rock engravings found in the Tafraoute area are the Carved Gazelles, 2km away in the village of Tazekka. There are actually two gazelles: one on the upturned face of a fallen boulder, and another on a larger boulder above eye height. They're large, prominent and quite elegant.
It's a pleasant mountain-bike ride or walk 2km from central Tafraoute. The easiest way to find it is to walk along Route de Tazekka to Camping Tazka on the Tiznit road (R104), and ask the jovial Anglophone Mohamed for directions once you arrive.